Pipe couplings are know for the joining of the ends of pipe sections. A shield of a pipe coupling compresses a gasket against pipe sections to be joined by the tightening of bands around the shield.
In U.S. Pat. No. 3,233,922 to Evans, a joint is provided for sections of cast iron pipes having substantially identical ends arranged in alignment. A coupling band is applied around the adjacent pipe ends to effect a pressure tight seal without appreciably increasing the total outer diameter of the pipe sections to be joined. An annular resilient packing member is placed over the ends of the pipes to be joined, on top of which is placed the coupling band. The coupling band overlaps and surrounds the adjacent ends of the pipe sections. The annular resilient packing member is interposed between the coupling band and the pipe ends and bridges the pipe ends. The packing member is of a width substantially the same as that of the coupling band and the packing member is provided on the inner surface of the coupling band and has an annular raised ridge fitting between the aligned pipe ends to prevent contact of the pipe ends. The coupling band holds the pipe ends together to form a joint and also compresses the packing member tightly around both ends to seal the joint. The band is made of a high-quality stainless steel and is provided with a series of transversely extending corrugations throughout the entire length of the coupling band. The corrugations are placed around the pipes in alignment parallel to the longitudinal axis of the pipes. If the pipe sections are of slightly different diameters, the area of the coupling band surrounding the larger pipe section expands due to the flattening of the corrugations in that area. The coupling band tightens the adjacent pipe ends by the use of two tightening straps surrounding the coupling band adjacent to the edges of the band, to seal the joint by compressing the packing member.
U.S. Pat. No. 3,359,017 to Schaub, is an improvement over the patent to Evans. The pipe coupling consists of a corrugated sheet metal shield which is closed by clamping bands, with the shield ends overlapping an annular elastic gasket fitted over adjacent pipe ends. The overlapped shield end is flat and merges into a tapered shield portion formed by corrugations of progressively increasing height. This avoids increasing frictional resistance of the bands during the tightening of the straps.
The patent to Schaub discloses one end of the corrugated shield overlapping the other end of the shield in the direction of circumferential displacement of the clamping straps. A "reverse overlap" arrangement provides reduced frictional resistance of the surfaces contracting around the gasket surrounding the pipe ends. One end of the shield is substantially flat, being smooth on both sides and extending for a distance from the corrugated portion of the shield.
The tightening straps of the patents to Evans and Schaub are connected to the shield by rivets extending through both the coupling shield and the tightening straps or by welding of the coupling shield to the tightening straps.